Battery unit

ABSTRACT

A battery unit includes: a main accommodation casing that includes a power output terminal; at least one sub-module that is accommodated in the main accommodation casing; and a control unit that is accommodated in the main accommodation casing and controls at least one of charging and discharging of a unit battery, wherein in the sub-module, two or more battery blocks are accommodated inside a sub-accommodation casing so that the terminals of the battery blocks each including a plurality of unit batteries are not exposed and the battery blocks are connected to each other through an electric connection member.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2010-239849 filed on Oct. 26, 2010, the disclosure of which isincorporated herein by reference.

BACKGROUND

The present disclosure relates to a battery unit. Specifically, thedisclosure relates to a battery unit that includes a plurality ofbattery blocks.

In recent years, there has been a rapid expansion in the usage ofsecondary batteries such as a lithium ion battery as a storage batteryfor a vehicle, a solar battery, or a power storage battery combined witha new energy system such as wind power generation. In such a storagebattery, generally, a battery block is formed by connecting a pluralityof, for example, four unit batteries (called an electrical cell or acell and appropriately referred to as a battery in the followingdescription) to each other in parallel and/or in series. A plurality ofbattery blocks is accommodated in an external casing.

For example, Japanese Unexamined Patent Application Publication No.2009-289429 discloses a structure in which a battery accommodation boxas an external casing is divided by a division plate so as to form aplurality of battery accommodation spaces and a battery block isaccommodated in each battery accommodation space.

SUMMARY

However, it is inconvenient to attach the plurality of battery blocks toa battery accommodation casing. Furthermore, since the work ofelectrically connecting and assembling the battery blocks is performedinside the casing, there is a danger that short-circuiting occurs due tocomponents contacting and dropping during the work. Furthermore, whenvibration or impact is applied to a battery accommodation box after thebattery module is disposed inside the battery accommodation box, thefixed battery blocks may be separated from the fixed position, so thatthe batteries may be short-circuited to each other. Furthermore, whenthe battery accommodation box is formed of metal, there is a concernthat short-circuiting may occur between the battery and the batteryaccommodation box.

Accordingly, it is desirable to provide a battery unit for which thereis capability for performing efficient assembly work of the battery unitand short-circuiting during or after the assembly of the battery unitcan be prevented.

In order to solve the above-described problem, there is provided abattery unit including: a main accommodation casing that includes apower output terminal; at least one sub-module that is accommodated inthe main accommodation casing; and a control unit that is accommodatedin the main accommodation casing and controls at least one of chargingand discharging of a unit battery, wherein in the sub-module, two ormore battery blocks are accommodated inside a sub-accommodation casingso that the terminals of the battery blocks each including a pluralityof unit batteries are not exposed and the battery blocks are connectedto each other through an electric connection member.

According to at least one embodiment, the sub-module may be assembledoutside the main accommodation casing so that the positive and negativeelectrode terminals of the plurality of unit batteries constituting thebattery block are covered by the insulating sub-accommodation casing.Then, the plurality of sub-modules is inserted and disposed inside themain accommodation casing. Accordingly, the attachment work may befurther efficiently performed compared to the case where each batteryblock is attached into the main accommodation casing. Furthermore, sincethe assembly work of the battery block and the sub-module is performedoutside the accommodation casing, the worry of short-circuiting may bereduced during the attachment work.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present application will be described below in detailwith reference to the drawings.

FIG. 1 is a perspective view illustrating an example of an appearance ofa battery unit according to one embodiment.

FIG. 2 is an exploded perspective view illustrating an example of thebattery unit according to one embodiment.

FIG. 3 is a perspective view illustrating a state where an externalupper casing is detached.

FIG. 4 is a perspective view illustrating a state where the externalupper casing is detached.

FIG. 5 is a plan view illustrating a state where the external uppercasing is detached.

FIG. 6 is a perspective view illustrating a sub-module accommodatedinside an external casing.

FIG. 7 is a connection diagram illustrating a connection relation of abattery included in the battery unit.

FIG. 8 is a perspective view illustrating an example of a lower casingof the sub-module.

FIG. 9 is a perspective view illustrating a state where a battery blockis disposed with respect to the lower casing.

FIG. 10 is a perspective view illustrating an example of the sub-moduleconfigured to be covered by the upper casing.

FIG. 11 is a perspective view illustrating another example of the lowercasing and the battery block disposed with respect to the lower casing.

FIG. 12 is a perspective view illustrating another example of thesub-module provided to be covered by the upper casing.

FIG. 13 is an exploded perspective view illustrating an example of thebattery block.

FIGS. 14A, 14B, 14C are perspective views illustrating attachment of aheat radiation rubber.

FIGS. 15A and 15B are cross-sectional views illustrating the attachmentof the heat radiation rubber.

FIG. 16 is a perspective view illustrating an example of a structureprovided to attach a thermistor.

FIG. 17 is a perspective view illustrating an example of a heatingstructure. Additional features and advantages are described herein, andwill be apparent from the following Detailed Description and thefigures.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

DETAILED DESCRIPTION

Overall Structure of Battery Unit

Hereinafter, a battery unit will be described by referring to thedrawings.

FIGS. 1 to 5 are perspective views illustrating an overall structure ofa battery unit 1. An external casing 2 as a main accommodation casing ofthe battery unit 1 includes an external lower casing 2 a and an externalupper casing 2 b which are formed of metal by sheet-metal processing. Itis desirable to use a material having a high heat transfer rate and aradiation rate as a material of the external lower casing 2 a and theexternal upper casing 2 b. Accordingly, an excellent casing heatradiation property may be obtained, and an increase in temperatureinside the casing may be suppressed. Due to the excellent casing heatradiation property, an opening of the casing 2 may be minimized orremoved, and high dust-proofness and drip-proofness may be realized. Forexample, the material of the external lower casing 2 a and the externalupper casing 2 b may be aluminum, aluminum alloy, copper, or copperalloy. For example, the sheet thickness of each of the external lowercasing 2 a and the external upper casing 2 b may be about 1 mm or more.

The rear surface of the casing 2 is provided with an external positiveelectrode terminal 3 and an external negative electrode terminal 4 whichare used to perform charging and discharging of the battery unit 1. Ashort-circuit prevention wall 3 a is provided at both sides of theexternal positive electrode terminal 3 so as to prevent short-circuitingbetween terminals. A short-circuit prevention wall 4 a is provided atboth sides of the external negative electrode terminal 4 so as toprevent short-circuiting between terminals.

Furthermore, a current breaker 5 is provided at the rear surface of thebattery unit 1. Since the current breaker 5 is provided, the safety ofthe battery unit may improve. A malfunction prevention component 5 a isprovided around the current breaker 5. Furthermore, a connection portion6 is provided so as to be connected to a control circuit disposed insidethe casing 2. The control circuit is provided so as to monitor thetemperature of the battery unit and controls charging, discharging, andthe like. As shown in FIG. 4, a substrate of a control block 8 isaccommodated therein. Furthermore, the front surface of the casing 2 isprovided with a display element 7 such as an LED displaying an operationstate as shown in FIG. 4.

As shown in FIGS. 2 to 5, the external lower casing 2 a of the casing 2is formed in a box shape, and the external upper casing 2 b is providedso as to cover the opening thereof. Sub-modules AS1 to AS4 areaccommodated inside an accommodation space of the external lower casing2 a. As shown in FIG. 2, a plurality of bosses 9 is formed at the bottomsurface of the external lower casing 2 a so as to fix the sub-modulesAS1 to AS4 by threading or the like. The sub-modules AS1 to AS4 may beassembled in advance outside the casing 2.

FIG. 6 only shows the sub-modules AS1 to AS4. As shown in FIG. 6, eachsub-module is provided by integrating a plurality of battery blocksusing an insulation casing (an upper casing 11 and a lower casing 12) asa sub-accommodation casing. A molding component such as plastic may beused as the upper casing 11 and the lower casing 12. In the sub-modulesAS1 to AS4, the plurality of battery blocks is accommodated inside theupper casing 11 and the lower casing 12 so that the positive andnegative electrode terminals of the battery block are not exposed.

Each battery block is provided by connecting, for example, eightcylindrical lithium ion secondary batteries in parallel to each other.Each of the sub-modules AS1 and AS2 is provided by integrating sixbattery blocks through the upper casing 11 and the lower casing 12. Eachof the sub-modules AS3 and AS4 is provided by integrating two batteryblocks through the upper casing 11 and the lower casing 12. Accordingly,sixteen battery blocks are provided in total as understood by“6+6+2+2=16”. These battery blocks are connected to each other, forexample, in series.

Connection Between Battery Blocks

In each of the sub-modules AS1 to AS4, a connection metallic sheet, forexample, a bus-bar is used so as to connect the battery blocks to eachother in series. The bus-bar is thin and elongated bar-like metal. Thebus-bar is provided with a plurality of holes used for connection with aconnection metallic sheet or the like derived from the battery block.

As shown in FIG. 7, the battery blocks B1 to B16 (which areappropriately referred to as battery blocks B when it is not necessaryto distinguish the battery blocks) each having eight batteries connectedto each other in parallel are connected to each other in series. Thecharging and discharging of each of the battery blocks B1 to B16 iscontrolled while being connected to the control block 8. The chargingand discharging is performed through the external positive electrodeterminal 3 and the external negative electrode terminal 4. For example,the battery blocks B1 to B6 are included in the sub-module AS1, and thebattery blocks B11 to B16 are included in the sub-module AS2.Furthermore, the battery blocks B7 and B10 are included in thesub-module AS3, and the battery blocks B8 and B9 are included in thesub-module AS4.

Sub-Module

Referring to FIGS. 8, 9, and 10, the sub-module, for example, thesub-module AS1 will be described. Furthermore, the sub-module AS2 alsohas the same structure as that of the sub-module AS1. As shown in FIG.8, the lower casing 12 as a molding component is formed in a shallow boxshape with a side wall 31 provided in the periphery thereof. Theaccommodation portion of the lower casing 12 is segmented into sixaccommodation spaces SP1 to SP6 by ribs.

The battery blocks B have the same shape. The accommodation spaces SP1to SP6 formed in the lower casing 12 substantially have the sameoutlines of the bottom surfaces of the battery blocks B. The bottomsurface of the battery block B is a positive electrode terminal surfaceor a negative electrode terminal surface. The battery blocks B1 to B6are respectively accommodated in the accommodation spaces SP1 to SP6. Inthis case, the bottom surfaces of the battery blocks B are substantiallyformed in a rectangular shape, and a positive electrode metallic sheetand a negative electrode metallic sheet are respectively drawn out fromboth short sides thereof as described below. Accordingly, in theaccommodation spaces SP1 to SP6, the positive and negative polarities ofthe drawn portions exposed to the outside of the casing are reversed inaccordance with the accommodation direction of the battery block B. Thatis, the connection between the battery blocks may be appropriately setin accordance with the accommodation direction of the battery block B.

The bottom surface of the lower casing 12 and the ribs and the side wall31 may regulate the position of the battery block when the battery blockis accommodated therein. That is, the accommodation space may be formedso as to cover a part of the bottom surface and the peripheral surfaceof the battery block. Accordingly, even when external vibration orimpact is applied to the battery unit 1, so that it is transferred tothe battery block, the positional regulation of the battery may bemaintained and a high degree of safety may be obtained.

Three fastening portions 32 protrude from each of the bottom surfaces ofthe accommodation spaces SP1 to SP6 so as to attach the battery blocksthereto. The formation positions of the fastening portions 32 match thepositions of the gaps formed when arranging, for example, eightcylindrical batteries included in the battery block. Further, a shockabsorbing sheet 33 is disposed at the bottom surface, and the shockabsorbing sheet 33 is interposed between the bottom surface of thebattery block B and the bottom surface of the lower casing 12. Due tothe shock absorbing sheet 33, the battery block may be protected bypreventing impact or vibration applied to the battery unit 1 from beingdirectly transferred thereto. For example, when the battery unit 1 isvibrated, the shock absorbing sheet 33 may dampen the vibration. It isdesirable that the shock absorbing sheet 33 have a high shock absorptionproperty and a high heat transfer rate.

A connection portion 34 is provided so as to protrude outward from theside surface of the lower casing 12 in the lateral direction, and aconnection member used for the electric connection between the batteryblocks is disposed thereon. The connection member, for example, abus-bar 35 is disposed at the connection portion 34, and the bus-bar 35is fixed to the lower casing 12 by a screw. The battery blocks B1 to B6are connected to each other in series through the bus-bar 35. Asubstantially perpendicular sheet-like rib 36 is formed along the outerend of the bus-bar 35. Due to the sheet-like rib 36, the bus-bar 35disposed at the connection portion 34 does not easily contact the otherpositions.

As shown in FIG. 9, the battery blocks B1 to B6 are respectivelyinserted and disposed at the accommodation spaces SP1 to SP6 of thelower casing 12. For example, the battery block B6 is disposed at theaccommodation space SP6. The battery block B6 disposed at the lowercasing 12 is fixed to the lower casing 12 using the fastening portion32. The specific structure of the battery block B will be describedlater.

When a predetermined number of battery blocks B1 to B6 are attached tothe lower casing 12, as shown in FIG. 10, the battery blocks may becovered by the upper casing 11. The upper casing 11 is fixed to thebattery blocks B1 to B6 or the lower casing 12 by threading or the like,thereby assembling the sub-module AS1. The upper casing 11 is a plasticmolding component. The upper casing 11 covers the battery blocks B1 toB6 from the upside thereof so as to cover the entire portion exposed tothe upside from the lower casing 12 of the battery blocks B1 to B6accommodated in the lower casing 12. The upper surface sheet of theupper casing 11 is provided with four rectangular openings (referred toas slits) 41 a corresponding to the positions of the battery blocks. Aheat radiation rubber is inserted and disposed at each slit 41 a asdescribed below. Furthermore, the slit 41 b which is the same as theslit 41 a is formed on the bottom surface sheet of the lower casing 12.

Referring to FIGS. 11 and 12, the sub-modules AS3 and AS4 will bedescribed. As shown in FIG. 11, the sub-module AS3 and AS4 have thecommon lower casing 12 and the separate upper casings 11. The lowercasing 12 is formed in a shallow box shape with a side wall 31 providedin the periphery thereof. The accommodation portion of the lower casing12 is segmented into four accommodation spaces SP7 to SP10 by the ribsand the connection portions 34. The battery blocks B7 to B10 arerespectively accommodated in the accommodation spaces SP7 to SP10.

Three fastening portions 32 protrude from each bottom surface of theaccommodation spaces SP7 to SP10 so as to attach the battery blocksthereto. Further, the shock absorbing sheet 33 is disposed at the bottomsurface, and the shock absorbing sheet 33 is interposed between thebottom surface of the battery block B and the bottom surface of thelower casing 12. Due to the shock absorbing sheet 33, the battery blockmay be protected by preventing impact or vibration applied to thebattery unit 1 from being directly transferred thereto. For example,when the battery unit 1 is vibrated, the shock absorbing sheet 33 maydampen the vibration. It is desirable that the shock absorbing sheet 33have a high shock absorption property and a high heat transfer rate.

The bottom surface of the lower casing 12 and the ribs and the side wall31 may regulate the position of the battery block when the battery blockis accommodated therein. That is, the accommodation space may be formedso as to cover a part of the bottom surface and the peripheral surfaceof the battery block. Accordingly, even when external vibration orimpact is applied to the battery unit 1, so that it is transferred tothe battery block, the positional regulation of the battery may bemaintained and a high degree of safety may be obtained.

The connection portion 34 is provided so as to protrude outward from theside surface of the lower casing 12 in the longitudinal direction, and aconnection member used for the electric connection between the batteryblocks is disposed thereon. The connection member, for example, abus-bar 35 is disposed at the connection portion 34, and the bus-bar 35is fixed to the lower casing 12 by a screw. Further, the connectionportion 34 is formed even at the boundary position between theaccommodation spaces SP7 and SP10 and the accommodation spaces SP8 andSP9. The bus-bar 35 is disposed at the connection portion 34, and thebus-bar 35 is fixed by a screw. The battery blocks B7 to B10 areconnected to each other in series by the bus-bar 35. The substantiallyperpendicular sheet-like rib 36 is formed along the outer end of thebus-bar 35. Due to the sheet-like rib 36, the bus-bar 35 disposed at theconnection portion 34 does not easily contact the other positions.

As shown in FIG. 12, the battery blocks B7 to B10 are respectivelyinserted and disposed at the accommodation spaces SP7 to SP10 of thelower casing 12. The battery blocks B7 to B10 disposed at the lowercasing 12 are fixed to the lower casing 12 using the fastening portion32. When the battery blocks B7 to B10 are attached to the lower casing12, as shown in FIG. 12, the separated upper casings 11 cover thebattery blocks.

The upper casing 11 is fixed to the battery blocks B7 and B10 or thelower casing 12 by threading or the like, thereby assembling thesub-module AS3. The upper casing 11 is fixed to the battery blocks B8and B9 or the lower casing 12 by threading or the like, therebyassembling the sub-module AS4. The upper casing 11 is a plastic moldingcomponent. The upper casing 11 covers the battery blocks B7 and B10 soas to cover the entire part exposed to the upside from the lower casing12 of the battery blocks B7 and B10 accommodated in the lower casing 12.In this manner, the upper casing 11 covers the battery blocks B8 and B9.The upper surface sheet of the upper casing 11 is provided with fourslits 41 a corresponding to each battery block. The heat radiationrubber is inserted and disposed at the slit 41 a as described below.

As described above, the battery blocks are formed as the sub-module, andthe sub-module is attached inside the external casing. Accordingly, theplurality of battery blocks may be formed as the sub-module outside theexternal casing before assembling the sub-module inside the externalcasing. Accordingly, there are advantages as follows compared to thecase where the plurality of battery blocks is directly assembled to theexternal casing.

Since the plurality of battery blocks is assembled in the casing of thesub-module outside the external casing, the workability may improve.

Since the battery blocks may be connected and assembled outside themetallic external casing, there is no danger of short-circuiting causedby components contacting and dropping, and work may be safely performed.

Since the sub-module is used which accommodates the battery block in theinsulated molding casing, there is no danger of short-circuiting wheneach sub-module is assembled and disposed in the metallic externalcasing, and work may be safely performed.

Since the battery block is covered by the insulation casing even afterthe sub-module is disposed and fixed into the external casing, theinsulation against the external casing is ensured even when vibrationand impact are applied thereto, thereby ensuring safety.

Battery Block

FIG. 13 is a perspective view illustrating an example of a structure ofthe battery block B. The battery block B includes a plurality of, forexample, eight batteries 21, a battery holder 22, a positive electrodemetallic sheet 23 a, and a negative electrode metallic sheet 23 b, andthe battery block B is assembled by these components. As the batteryholder 22, for example, an insulating material such as plastic may beexemplified.

The battery 21 is, for example, a cylindrical battery having a positiveelectrode terminal portion 21 a and a negative electrode terminalportion 21 b provided at both ends thereof. Furthermore, the shape ofthe battery is not limited to the cylindrical shape, and batteries withvarious shapes such as a square shape may be used. The battery 21 is,for example, a secondary battery which may be repeatedly used. As such asecondary battery, for example, a lithium ion secondary battery, alithium ion polymer secondary battery, or the like may be exemplified.

It is desirable to use coppery alloy or a material similar thereto asthe material of the positive electrode metallic sheet 23 a and thenegative electrode metallic sheet 23 b. Accordingly, an interconnectionmay be performed with low resistance. For example, the material of eachof the positive electrode metallic sheet 23 a and the negative electrodemetallic sheet 23 b may be nickel or nickel alloy. Accordingly, thepositive electrode metallic sheet 23 a and the negative electrodemetallic sheet 23 b may be satisfactorily welded to the positiveelectrode terminal portion 21 a and the negative electrode terminalportion 21 b of the battery 21. For example, the surface of the materialof each of the positive electrode metallic sheet 23 a and the negativeelectrode metallic sheet 23 b may be subjected to plating of tin ornickel. Accordingly, it is possible to prevent rust from being generateddue to the oxidization of the surface of the material of each of thepositive electrode metallic sheet 23 a and the negative electrodemetallic sheet 23 b.

The positive electrode terminal portions and the negative electrodeterminal portions of the plurality of batteries 21 are arranged on thesame surface. For example, one-side ends corresponding to the positiveelectrode terminal portions 21 a of the plurality of batteries 21 may befixed by the battery holder 22, and the other-side ends corresponding tothe negative electrode terminal portions 21 b may be fixed by thenegative electrode metallic sheet 23 b. The positive electrode metallicsheet 23 a is provided with three holes 24, and the negative electrodemetallic sheet 23 b is provided with three holes 25. Furthermore, thebattery holder is also provided with three holes. These holes arerespectively provided at positions corresponding to the positions of thefastening portions 32 protruding from the bottom surface of the lowercasing 12. The fastening portions 32 penetrate the gaps in thearrangement of the batteries 21. Accordingly, the battery block B may befixed to the lower casing 12 by a screw even in the state where thebattery block B is accommodated in the accommodation space of the lowercasing 12.

A notch 27 is formed at the upper surface sheet of the battery holder22, and a notch 28 is formed at the positive electrode metallic sheet 23a so as to correspond to the notch 27. An attachment concave portion(not shown) is formed at a part of the upper surface of the batteryholder 22 below the notches 27 and 28 so as to be opened toward theupper end. As described below, the concave portion is provided so as toattach a temperature detection element, for example, a thermistor to theperipheral surface of the battery 21.

The positive electrode metallic sheet 23 a is disposed on the batteryholder 22 fixing one end of the battery 21, and the positive electrodeterminals 21 a of the plurality of batteries 21 is mechanically andelectrically connected to the positive electrode metallic sheet 23 a. Onthe other hand, the negative electrode metallic sheet 23 b is disposedso as to fix the other end of the battery 21, and the negative electrodeterminal portions 21 b of the plurality of batteries 21 is mechanicallyand electrically connected to the negative electrode metallic sheet 23b. When the positive electrode metallic sheet 23 a and the negativeelectrode metallic sheet 23 b are disposed in this manner, the pluralityof batteries 21 are electrically connected to each other in parallel.

Since both ends of the plurality of batteries 21 are fixed by theaccommodation space of the lower casing 12 and the battery holder 22,when vibration or impact is applied to the battery unit 1, the contactpoint between the positive electrode terminal portion 21 a and thepositive electrode metallic sheet 23 a and the contact portion betweenthe negative electrode terminal portion 21 b and the negative electrodemetallic sheet 23 b may be protected. Further, it is possible toinsulate the portion having polarity opposite to the polarity of thecontact point between the positive electrode metallic sheet 23 a and thenegative electrode metallic sheet 23 b due to the battery holder 22 andthe lower casing 12. For example, the battery holder 22 electricallyinsulates the positive electrode metallic sheet 23 a from the negativeelectrode portion of the battery 21.

The positive electrode metallic sheet 23 a is formed in an L-shape as awhole. The positive electrode metallic sheet 23 a includes a terminalconnection portion and a drawn portion 26 a bent with respect to theterminal connection portion. One peripheral surface of the terminalconnection portion is mechanically and electrically bonded to thepositive electrode terminal portions 21 a of the plurality of batteries21 fixed by the battery holder 22. As the bonding method, for example,electrical resistance welding or welding using heat generated by a laserbeam may be exemplified, but the disclosure is not particularly limitedto these methods. For example, an ordinary welding method may beappropriately used. The tip of the drawn portion 26 a is provided with aconnection portion which is uprightly formed with respect to the drawnportion 26 a. The connection portion is provided with one or a pluralityof screw holes.

The negative electrode metallic sheet 23 b is formed in an L-shape as awhole. The negative electrode metallic sheet 23 b includes a terminalconnection portion and a drawn portion 26 b bent with respect to theterminal connection portion. One peripheral surface of the terminalconnection portion is mechanically and electrically bonded to thenegative electrode terminal portions 21 b of the plurality of batteries21. As the bonding method, for example, electrical resistance welding orwelding using heat generated by a laser beam may be exemplified, but thedisclosure is not particularly limited to these methods. For example, anordinary welding method may be appropriately used. The tip of the drawnportion 26 b is provided with a connection portion which is uprightlyformed with respect to the drawn portion 26 b. The connection portion isprovided with one or a plurality of screw holes.

The drawn portion 26 a of the positive electrode metallic sheet 23 a andthe drawn portion 26 b of the negative electrode metallic sheet 23 b arerespectively drawn outward in the vertical direction of the plurality ofbatteries 21 arranged according to the matrix of 2 by 4, and are derivedfrom the opposite surfaces of the arranged batteries. When the batteryblock B is rotated by 180°, the drawing direction of the positiveelectrode metallic sheet 23 a and the negative electrode metallic sheet23 b may be reversed.

Thermistor Attachment Structure

Referring to FIGS. 14A, 14B, and 14C, a thermistor attachment structurewill be described. FIG. 14B is a diagram magnifying a part XIVB of FIG.14A, and FIG. 14C is a diagram magnifying a part XIVC of FIG. 14A. Asshown in FIG. 14C, a slit-like notch 51 is formed so as to extenddownward from the edge of the upper surface of the upper casing 11 ofeach sub-module, for example, the sub-module AS1. The notch 51 is formedat one position (or two positions including the opposite one position)of each battery block constituting the sub-module AS1. The position ofthe notch 51 is the same as the position of the notch 27 of the batteryholder 22 and the position of the notch 28 of the positive electrodemetallic sheet 23 a.

An attachment concave portion 52 is formed above the notches and withinthe width of the notch 51 so as to be notched downward from the upperend surface of the battery holder 22. The lower edge of the concaveportion 52 is provided with a slit 53. Specifically, a thermistorelement and a connector are mounted on a small substrate. A thermistoris attached by inserting the substrate into the slit 53. The peripheralsurface of the inner battery 21 is exposed through the concave portion52, and whether the thermistor is bonded to the battery from the outsidemay be reliably checked. The substrate inserted into the slit 53 of theconcave portion 52 is thermally bonded to the peripheral surface of thebattery. The substrate having a thermistor and a connector mountedthereon is bonded to the peripheral surface of the battery 21 by, forexample, an adhesive with a satisfactory heat transfer property.Furthermore, the thermistor may be directly attached without using thesubstrate.

The battery holder 22 below the concave portion 52 is provided with alocking sheet 54 having a hole. The locking sheet 54 is provided to fixa lead wire. Furthermore, the lead wire is connected to the control unitinside the control block 8 through the bus-bar or the like. Such athermistor attachment structure may enable the attachment or detachmentof the thermistor for maintenance even in the state where the sub-moduleis assembled and the battery 21 is covered by the casing.

Structure for Emitting Heat of Battery Inside Sub-Module

Generally, the battery inside the sub-module radiates heat during thecharging and discharging thereof, and the performance of the battery isgradually degraded. Accordingly, it is necessary to suppress heating orradiate heat. Furthermore, since a difference in temperature occurs dueto the arrangement place of the batteries, the batteries may not haveuniform performance.

In one embodiment, the degradation of the performance of the battery dueto heating is prevented, and a difference in temperature betweenbatteries is suppressed. As an example, in the sub-module AS1, forexample, as shown in FIGS. 15A and 15B, a slit 41 a is formed in theupper surface sheet of the upper casing 11. A slit 41 b is formed at thebottom surface sheet of the lower casing 12. Heat radiation rubbers 42 aand 42 b as shock absorbing and heat radiating portions are respectivelyfitted to the slits 41 a and 41 b, and are fixed thereto by adhering orthe like if necessary. The attachment of the heat radiation rubbers 42 aand 42 b with respect to the slits 41 a and 41 b is performed at theoutside of the external casing. The heat radiation rubbers 42 a and 42 bare formed of a material having a satisfactory heat transfer property, ashock absorbing characteristic, and a heat resistance property, forexample, silicon. Furthermore, the heat radiation rubbers 42 a and 42 bmay have a structure (for example, a laminated structure) formed by thecombination of a heat transfer material having a satisfactory heattransfer property and a shock absorbing material having a satisfactoryheat resistance property and a satisfactory shock absorbingcharacteristic. Moreover, the heat radiation rubbers 42 a and 42 b maybe integrally formed with the casings 11 and 12 when molding the casings11 and 12.

As shown in a schematic cross-sectional view of FIG. 16, the heatradiation rubber 42 b is interposed so as to bury a gap between thelower surface of each battery block of the sub-module AS1 and the innersurface of the external lower casing 2 a. The heat radiation rubber 42 ais interposed so as to bury a gap between the upper surface of eachbattery block of the sub-module AS1 and the inner surface of theexternal upper casing 2 b. Heat generated from the battery of thesub-module AS1 is radiated through the heat radiation rubbers 42 a and42 b to the outside of the metallic external casing (2 a and 2 b).Furthermore, although the sub-module AS1 is described, the othersub-modules AS2, AS3, and AS4 also have the same heat radiationstructure.

In such a heat radiation structure, since four slits and four heatradiation rubbers are disposed at the upper and lower surfaces of eachbattery block, the heat may be highly efficiently and uniformly radiatedin the overall battery unit. Furthermore, since the heat radiationrubbers 42 a and 42 b have a satisfactory shock absorbingcharacteristic, the battery may be protected from vibration and impactdue to dropping. Furthermore, since an opening such as a slit isprovided in the casing of the sub-module and the heat radiation rubberis disposed at the opening, the position of the heat radiation rubber isregulated by the opening, thereby preventing a deviation of the positionof the heat radiation rubber.

Structure of Heating Battery Inside Sub-Module

Generally, the battery inside the sub-module is gradually degraded whenbeing charged in a low-temperature environment (for example, 0° C. orless). Further, in the case of discharging, the internal resistanceincreases, so that the capacitance reduces. Likewise, there was aproblem in that the performance of the battery was not sufficientlyexhibited in the low-temperature environment. In one embodiment, thedamage of the performance of the battery is prevented even when thecharging and discharging is performed in the low-temperatureenvironment.

As shown in FIG. 17, a flat heater 61 is disposed at the bottom surfaceof the external lower casing 2 a of the battery unit. The heater 61 isprovided so as to adhere to the bottom surface. It is desirable that theheater 61 have sufficient heating performance, a thin thickness, andflexibility. As an example, since a silicon rubber heater has anextremely thin thickness and flexibility, such a condition may besatisfied. Furthermore, the heater may be provided at the upper surfaceof the external upper casing 2 b, and the heater may be provided at boththe upper and lower surfaces of the external casing (2 a and 2 b). Theheater 61 is driven in accordance with the ambient temperature or thetemperature of the battery. For example, when the ambient temperaturebecomes around 0° C., the driving of the heater 61 is started. Then,when the ambient temperature or the temperature of the battery becomesmore than a predetermined value, the operation is stopped.

In one embodiment, since the heat radiation rubbers 42 a and 42 b areprovided, heat generated by the heater 61 may be easily and uniformlytransferred to the batteries inside the sub-module. Accordingly, adeviation in temperature due to the arrangement or the positions of thebatteries inside the casing may be suppressed as much as possible, anddegradation of the performance of the battery may be prevented.

As described above, since the temperature detection element (thermistor)is attached to the battery of each battery block, a temperature controlmay be highly efficiently performed when radiating heat from the batteryor heating the battery.

MODIFIED EXAMPLE

While one embodiment of the disclosure has been specifically described,the disclosure is not limited to the above-described embodiment, andvarious modifications based on the technical spirit of the disclosuremay be made. For example, in the battery block, the negative electrodeterminal portion 21 b of the battery 21 is connected by the negativeelectrode metallic sheet 23 b, but a structure may be adopted in whichthe negative electrode side is held by the battery holder and thepositive electrode side is connected by the positive electrode metallicsheet 23 a. Furthermore, the structure, the method, the shape, thematerial, and the like exemplified in the above-described embodiment aremerely an example, and if necessary, a structure, method, shape,material, numerical value, and the like different therefrom may be used.Further, the respective structures of the above-described embodiment maybe combined with each other as long as it does not deviate from thespirit of the disclosure.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The application is claimed as follows:
 1. A battery unit comprising: amain accommodation casing that includes a power output terminal; aplurality of sub-modules accommodated in the main accommodation casing,wherein each sub-module includes a plurality of battery blocks, and eachbattery block includes a plurality of unit batteries connected to eachother, a battery holder, a negative electrode terminal, and a positiveelectrode terminal, the positive electrode terminal including a metallicsheet with a plurality of connection points to a positive electrodeterminal of each of the plurality of unit batteries disposed on thebattery holder, wherein the battery holder includes a notch formed in asurface of the battery holder that contacts the metallic sheet of thepositive electrode terminal and wherein the battery holder furthercomprises, below a concave portion, a locking having a hole, the lockingsheet provided in a location adjacent to the notch; an upper insulationcasing configured to cover the plurality of battery blocks accommodatedwithin each sub-module from an upside thereof so as to cover the entireportion exposed to the upside from a lower insulation casing into whichthe battery blocks are respectively inserted, wherein the positive andnegative electrode terminals of each battery block are covered by theupper and lower insulation casings such that each sub-module iselectrically isolated from each other; and a control unit that isaccommodated in the main accommodation casing and controls at least oneof charging and discharging of each of the plurality of battery blocksincluding the plurality of unit batteries, wherein the battery blocksare electrically connected to each other in series through an electricconnection member that is fixed to the lower insulation casing.
 2. Thebattery unit according to claim 1, wherein the upper and lowerinsulation casings constitute a sub-accommodation casing of thesub-module is segmented into an upper casing and a lower casing.
 3. Thesub-module according to claim 1, wherein the plurality of unit batteriesare fixed by the battery holder, which is formed of an insulatingmaterial.
 4. The battery block according to claim 1, wherein theplurality of unit batteries are fixed by the positive electrode metallicsheet.
 5. The battery block according to claim 1, wherein a shockabsorbing and heat radiating portion having a heat transfer property anda shock absorbing characteristic is interposed between an inner surfaceof the main accommodation casing and the sub-module.
 6. The batteryblock according to claim 5, wherein a plurality of openings is formed inat least one of an upper surface and a bottom surface of asub-accommodation casing comprising the upper and lower insulationcasings, and the shock absorbing and heat radiating portion is disposedfor each opening.
 7. The battery unit according to claim 1, wherein aplurality of holes is formed in a sub-accommodation casing comprisingthe upper and lower insulation casings, and a temperature detectionelement is attached to a surface of an inner battery through the holes.8. The battery unit according to claim 7, wherein the temperaturedetection element is attached to a surface of the unit battery through aconnection member having a heat transfer property.
 9. The battery unitaccording to claim 1, wherein a flat heat radiation portion is disposedin at least one of a bottom surface and an upper surface of the mainaccommodation casing.